A222201 Write n=3i+j, 0<=j<3; a(n) = number of Hamiltonian cycles on square grid of points of size 2i+2 X 2i+2 (if j=0), 2i+2 X 2i+3 (j=1) or 2i+3 X 2i+4 (j=2).

1, 1, 2, 6, 14, 154, 1072, 5320, 301384, 4638576, 49483138, 13916993782, 467260456608, 10754797724124, 14746957510647992, 1076226888605605706, 53540340738182687296, 354282765498796010420944, 56126499620491437281263608, 6040964455632840415885507728, 191678405883294971709423926242394, 65882516522625836326159786165530572

Offset: 0

Author

N. J. A. Sloane, Feb 14 2013

Keywords

• nonn

Comments

An interleaving of A003763 and A222200.

Links

• Peter Tittmann, Enumeration in graphs: counting Hamiltonian cycles [Broken link?]
• Peter Tittman, Illustration of a(4) = 14 [Taken from preceding link]
• Peter Tittmann, Enumeration in graphs: counting Hamiltonian cycles [Backup copy of top page only, on the Internet Archive]
• Index entries for sequences related to graphs, Hamiltonian

Crossrefs

Cf. A003763, A222200.